JP3030149B2 - Non-aqueous electrolyte battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous electrolyte battery.
The present invention relates to a binder used for producing a negative electrode.

[0002]

2. Description of the Related Art Non-aqueous electrolyte batteries using a chargeable / dischargeable positive electrode and a negative electrode containing lithium as an active material have been attracting attention for their high energy density and excellent storage characteristics. Development is taking place. However, since this type of battery uses an organic solvent for the electrolytic solution, it has low conductivity and is inferior in high-rate characteristics as compared with an aqueous solution system. Therefore, the thickness of the positive and negative electrodes is reduced, and the electrode area is increased so that a high current can be obtained. At present, a method has been adopted in which the active material mixture is applied in the form of slurry to the surface of a core material made of a metal foil.

[0003] On the other hand, in such a method of applying a slurry of an active material mixture to the surface of a core material, it is important to select a binder and a solvent for dissolving or dispersing the binder. Polyvinylidene fluoride is used as the adhesive.

[0004]

However, the melting point of this polyvinylidene fluoride is as low as about 150 ° C., and the heat treatment temperature after the application of the active material mixture is limited. Had a big problem that could not be removed.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is intended to use a polytriol as a binder used in forming a positive electrode and a negative electrode of a non-aqueous electrolyte battery. Fluoroethylene (ethylene trifluoride resin) is used.

[0006]

[Function] Since the melting point of polytrifluoroethylene (ethylene trifluoride resin) is as high as about 250 ° C., heat treatment after slurry application of the active material mixture onto the surface of the electrode core material can be performed at a high temperature. Moisture and impurities can be sufficiently removed, and storage characteristics and cycle characteristics can be improved.

[0007]

The present invention will be described in detail below with reference to a comparison between examples of the battery of the present invention and comparative examples.

Embodiment 1 FIG. 1 is a central longitudinal sectional view of a cylindrical non-aqueous electrolyte secondary battery as one embodiment of the present invention. The negative electrode 1 and the positive electrode 2 were spirally wound via the separator 3 to assemble a cylindrical battery.

The negative electrode 1 is a car capable of absorbing and releasing lithium.
To 95% by weight of carbon, 5% by weight of polytrifluoroethylene (ethylene trifluoride resin) as a binder,
It is made into a slurry using N-methyl-2-pyrrolidone as a solvent and is applied to both surfaces of a copper foil as a core material. The negative electrode 1 is joined to a negative electrode can 4 with a negative electrode lead 5.

The positive electrode 2 comprises 90% by weight of cobalt oxide as a chargeable / dischargeable active material, 5% by weight of acetylene black as a conductive agent and 5% by weight of polytrifluoroethylene (ethylene trifluoride resin) as a binder. Like the negative electrode, the slurry was made into a slurry and applied to both sides of an aluminum foil as a core material to form electrodes. This was joined to the positive electrode cap 6 with the lead 7. At this time, both the positive and negative electrodes 1,
2 is dried by heat treatment at about 200 ° C. in a vacuum. The separator 3 is composed of a polypropylene porous film, and a mixture of propylene carbonate and dimethyl carbonate (50:50 vol%) is mixed with lithium hexafluorophosphate (fluorine-based lithium Lewis acid) as a lithium salt.
Electrolyte dissolved at a rate of mol / liter is impregnated. Reference numeral 8 denotes an insulating packing, and the battery has a diameter of 1
4.2 mm, height 50 mm. The battery thus prepared was designated as Battery A of the present invention.

Comparative Example 1 A battery similar to that of Example 1 was prepared except that polyvinylidene fluoride was used as a binder. At this time, the positive and negative electrodes 1 and 2 were heat-treated and dried in a vacuum at about 120 ° C. And this battery is compared with the comparative battery W
And

Comparative Example 2 A battery similar to Comparative Example 1 was prepared except that both the positive and negative electrodes were vacuum-dried at about 200 ° C. This battery was used as Comparative Battery X.

Using these batteries A, W and X, discharge characteristics before and after storage were examined. The conditions at this time were that each battery was stored in a charged state at 60 ° C. for 20 days, and then the discharge current was 100 mA.
Is to be discharged. The result is shown in FIG. From the storage characteristic diagram of FIG. 2, the battery A of the present invention was compared with the comparative batteries W and X
It is understood that the storage characteristics are superior to those of the above.

Next, cycle characteristics which are basic characteristics of the secondary battery were compared. The charge / discharge conditions at this time were a charge / discharge current of 100 mA and a cycle life of the battery when the initial capacity was reduced by 80%. The result is shown in FIG. From the cycle characteristic diagram of FIG. 3, the battery A of the present invention is comparative battery W, X
It can be seen that the cycle characteristics are superior to those of the above.

Example 2 A chargeable / dischargeable manganese oxide was used for the positive electrode 2, a mixture of propylene carbonate and γ-butyrolactone (30: 70% by volume) was used as an organic solvent, and tetrafluoroborane was used as a solute. A battery was prepared in the same manner as in Example 1 except that lithium oxide was used and methylformamide was used as a solvent for dissolving the binder. This battery was designated as Battery B of the invention.

Comparative Example 3 A battery similar to that of Example 2 was prepared except that polyvinylidene fluoride was used as a binder. At this time, the positive and negative electrodes 1 and 2 were heat-treated and dried at about 120 ° C. in a vacuum. This battery was designated as Comparative Battery Y.

Comparative Example 4 A battery similar to that of Comparative Example 3 was prepared except that both the positive and negative electrodes were vacuum-dried at about 200 ° C. This battery was designated as Comparative Battery Z.

Using these batteries B, Y and Z, cycle characteristics were compared. The charge / discharge conditions at this time were a charge / discharge current of 100 mA and a cycle life of the battery when the initial capacity was reduced by 80%. The result is shown in FIG. From FIG. 4, it can be seen that the battery B of the present invention has superior cycle characteristics as compared with the comparative batteries Y and Z.

As a solvent for dissolving or dispersing polytrifluoroethylene as a binder, methyl ethyl ketone and ethyl acetate can be used in addition to N-methyl-2-pyrrolidone and methylformamide.

In addition to lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium hexafluoroarsenate, and lithium hexafluoroantimonate as solutes of the nonaqueous electrolyte solution. And lithium perchlorate can be used as well.

[0021]

As is clear from the above description, the present invention uses polytrifluoroethylene (ethylene trifluoride resin) as a binder used when preparing the positive and negative electrodes of a non-aqueous electrolyte battery. Therefore, the storage characteristics and cycle characteristics of this type of battery can be improved, and its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a battery of the present invention.

FIG. 2 is a graph showing storage characteristics of a battery A of the present invention and comparative batteries W and X.

FIG. 3 is a cycle characteristic diagram of a battery A of the present invention and comparative batteries W and X.

FIG. 4 is a cycle characteristic diagram of a battery B of the present invention and comparative batteries Y and Z.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Negative electrode 2 Positive electrode 3 Separator A, B Battery of this invention, W, X, Y, Z Comparative battery.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masatoshi Takahashi 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Hiroshi Watanabe 2-18-18 Keihanhondori, Moriguchi-shi, Osaka (56) References JP-A-3-225751 (JP, A) JP-A-63-72065 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4 / 36-4/62 H01M 4/02-4/04 H01M 10/40

Claims (5)

(57) [Claims] 1. A battery comprising a chargeable / dischargeable positive electrode, a negative electrode using lithium as an active material, and a non-aqueous electrolyte,
These positive and negative electrodes are characterized in that the positive and negative electrode active materials are coated and dried on a core material made of metal foil using polytrifluoroethylene (ethylene trifluoride resin) as a binder. Non-aqueous electrolyte battery. 2. The non-aqueous electrolyte battery according to claim 1, wherein N-methyl-2-pyrrolidone, methyl ethyl ketone, ethyl acetate, and methylformamide are used as a solvent for dissolving or dispersing the binder. 3. The non-aqueous electrolyte battery according to claim 1, wherein the positive electrode is a manganese oxide, an iron oxide, a nickel oxide, or a cobalt oxide. 4. The non-aqueous electrolyte according to claim 1, wherein the negative electrode is an alloy, an oxide, or carbon capable of inserting and extracting lithium. battery. 5. The solute of the non-aqueous electrolyte comprises lithium trifluoromethanesulfonate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium hexafluoroantimonate, and lithium perchlorate. 3. The method according to claim 1, wherein at least one selected from a group is selected.
The non-aqueous electrolyte battery according to claim 3.